Changing a number of functions to aggregate argument character sets

and collations from the global name space into private and protected methods in Item_func_or_sum.

Author: Alexander Barkov

sql/item.cc

@@ -2035,8 +2035,9 @@ void my_coll_agg_error(Item** args, uint count, const char *fname,
 }
 
 
-bool agg_item_collations(DTCollation &c, const char *fname,
- Item **av, uint count, uint flags, int item_sep)
+bool Item_func_or_sum::agg_item_collations(DTCollation &c, const char *fname,
+ Item **av, uint count,
+ uint flags, int item_sep)
 {
  uint i;
  Item **arg;
@@ -2081,16 +2082,10 @@ bool agg_item_collations(DTCollation &c, const char *fname,
 }
 
 
-bool agg_item_collations_for_comparison(DTCollation &c, const char *fname,
- Item **av, uint count, uint flags)
-{
- return (agg_item_collations(c, fname, av, count,
- flags | MY_COLL_DISALLOW_NONE, 1));
-}
-
-
-bool agg_item_set_converter(DTCollation &coll, const char *fname,
- Item **args, uint nargs, uint flags, int item_sep)
+bool Item_func_or_sum::agg_item_set_converter(const DTCollation &coll,
+ const char *fname,
+ Item **args, uint nargs,
+ uint flags, int item_sep)
 {
  Item **arg, *safe_args[2]= {NULL, NULL};
 
@@ -2167,46 +2162,6 @@ bool agg_item_set_converter(DTCollation &coll, const char *fname,
 }
 
 
-/* 
- Collect arguments' character sets together.
- We allow to apply automatic character set conversion in some cases.
- The conditions when conversion is possible are:
- - arguments A and B have different charsets
- - A wins according to coercibility rules
- (i.e. a column is stronger than a string constant,
- an explicit COLLATE clause is stronger than a column)
- - character set of A is either superset for character set of B,
- or B is a string constant which can be converted into the
- character set of A without data loss.
- 
- If all of the above is true, then it's possible to convert
- B into the character set of A, and then compare according
- to the collation of A.
- 
- For functions with more than two arguments:
-
- collect(A,B,C) ::= collect(collect(A,B),C)
-
- Since this function calls THD::change_item_tree() on the passed Item **
- pointers, it is necessary to pass the original Item **'s, not copies.
- Otherwise their values will not be properly restored (see BUG#20769).
- If the items are not consecutive (eg. args[2] and args[5]), use the
- item_sep argument, ie.
-
- agg_item_charsets(coll, fname, &args[2], 2, flags, 3)
-
-*/
-
-bool agg_item_charsets(DTCollation &coll, const char *fname,
- Item **args, uint nargs, uint flags, int item_sep)
-{
- if (agg_item_collations(coll, fname, args, nargs, flags, item_sep))
- return TRUE;
-
- return agg_item_set_converter(coll, fname, args, nargs, flags, item_sep);
-}
-
-
 void Item_ident_for_show::make_field(Send_field *tmp_field)
 {
  tmp_field->table_name= tmp_field->org_table_name= table_name;

sql/item.h

@@ -2153,38 +2153,6 @@ class Item_name_const : public Item
  }
 };
 
-bool agg_item_collations(DTCollation &c, const char *name,
- Item **items, uint nitems, uint flags, int item_sep);
-bool agg_item_collations_for_comparison(DTCollation &c, const char *name,
- Item **items, uint nitems, uint flags);
-bool agg_item_set_converter(DTCollation &coll, const char *fname,
- Item **args, uint nargs, uint flags, int item_sep);
-bool agg_item_charsets(DTCollation &c, const char *name,
- Item **items, uint nitems, uint flags, int item_sep);
-inline bool
-agg_item_charsets_for_comparison(DTCollation &c, const char *name,
- Item **items, uint nitems,
- int item_sep= 1)
-{
- uint flags= MY_COLL_ALLOW_SUPERSET_CONV |
- MY_COLL_ALLOW_COERCIBLE_CONV |
- MY_COLL_DISALLOW_NONE;
- return agg_item_charsets(c, name, items, nitems, flags, item_sep);
-}
-inline bool
-agg_item_charsets_for_string_result_with_comparison(DTCollation &c,
- const char *name,
- Item **items, uint nitems,
- int item_sep= 1)
-{
- uint flags= MY_COLL_ALLOW_SUPERSET_CONV |
- MY_COLL_ALLOW_COERCIBLE_CONV |
- MY_COLL_ALLOW_NUMERIC_CONV |
- MY_COLL_DISALLOW_NONE;
- return agg_item_charsets(c, name, items, nitems, flags, item_sep);
-}
-
-
 class Item_num: public Item_basic_constant
 {
 public:
@@ -3616,7 +3584,50 @@ class Used_tables_and_const_cache
 */
 class Item_func_or_sum: public Item_result_field, public Item_args
 {
+ bool agg_item_collations(DTCollation &c, const char *name,
+ Item **items, uint nitems,
+ uint flags, int item_sep);
+ bool agg_item_set_converter(const DTCollation &coll, const char *fname,
+ Item **args, uint nargs,
+ uint flags, int item_sep);
 protected:
+ /*
+ Collect arguments' character sets together.
+ We allow to apply automatic character set conversion in some cases.
+ The conditions when conversion is possible are:
+ - arguments A and B have different charsets
+ - A wins according to coercibility rules
+ (i.e. a column is stronger than a string constant,
+ an explicit COLLATE clause is stronger than a column)
+ - character set of A is either superset for character set of B,
+ or B is a string constant which can be converted into the
+ character set of A without data loss.
+
+ If all of the above is true, then it's possible to convert
+ B into the character set of A, and then compare according
+ to the collation of A.
+
+ For functions with more than two arguments:
+
+ collect(A,B,C) ::= collect(collect(A,B),C)
+
+ Since this function calls THD::change_item_tree() on the passed Item **
+ pointers, it is necessary to pass the original Item **'s, not copies.
+ Otherwise their values will not be properly restored (see BUG#20769).
+ If the items are not consecutive (eg. args[2] and args[5]), use the
+ item_sep argument, ie.
+
+ agg_item_charsets(coll, fname, &args[2], 2, flags, 3)
+ */
+ bool agg_arg_charsets(DTCollation &c, Item **items, uint nitems,
+ uint flags, int item_sep)
+ {
+ if (agg_item_collations(c, func_name(), items, nitems, flags, item_sep))
+ return true;
+
+ return agg_item_set_converter(c, func_name(), items, nitems,
+ flags, item_sep);
+ }
  /*
  Aggregate arguments for string result, e.g: CONCAT(a,b)
  - convert to @@character_set_connection if all arguments are numbers
@@ -3629,7 +3640,7 @@ class Item_func_or_sum: public Item_result_field, public Item_args
  uint flags= MY_COLL_ALLOW_SUPERSET_CONV |
  MY_COLL_ALLOW_COERCIBLE_CONV |
  MY_COLL_ALLOW_NUMERIC_CONV;
- return agg_item_charsets(c, func_name(), items, nitems, flags, item_sep);
+ return agg_arg_charsets(c, items, nitems, flags, item_sep);
  }
  /*
  Aggregate arguments for string result, when some comparison
@@ -3646,7 +3657,48 @@ class Item_func_or_sum: public Item_result_field, public Item_args
  MY_COLL_ALLOW_COERCIBLE_CONV |
  MY_COLL_ALLOW_NUMERIC_CONV |
  MY_COLL_DISALLOW_NONE;
- return agg_item_charsets(c, func_name(), items, nitems, flags, item_sep);
+ return agg_arg_charsets(c, items, nitems, flags, item_sep);
+ }
+
+ /*
+ Aggregate arguments for comparison, e.g: a=b, a LIKE b, a RLIKE b
+ - don't convert to @@character_set_connection if all arguments are numbers
+ - don't allow DERIVATION_NONE
+ */
+ bool agg_arg_charsets_for_comparison(DTCollation &c,
+ Item **items, uint nitems,
+ int item_sep= 1)
+ {
+ uint flags= MY_COLL_ALLOW_SUPERSET_CONV |
+ MY_COLL_ALLOW_COERCIBLE_CONV |
+ MY_COLL_DISALLOW_NONE;
+ return agg_arg_charsets(c, items, nitems, flags, item_sep);
+ }
+
+
+public:
+ // This method is used by Arg_comparator
+ bool agg_arg_charsets_for_comparison(CHARSET_INFO **cs, Item **a, Item **b)
+ {
+ DTCollation tmp;
+ if (tmp.set((*a)->collation, (*b)->collation, MY_COLL_CMP_CONV) ||
+ tmp.derivation == DERIVATION_NONE)
+ {
+ my_error(ER_CANT_AGGREGATE_2COLLATIONS,MYF(0),
+ (*a)->collation.collation->name,
+ (*a)->collation.derivation_name(),
+ (*b)->collation.collation->name,
+ (*b)->collation.derivation_name(),
+ func_name());
+ return true;
+ }
+ if (agg_item_set_converter(tmp, func_name(),
+ a, 1, MY_COLL_CMP_CONV, 1) ||
+ agg_item_set_converter(tmp, func_name(),
+ b, 1, MY_COLL_CMP_CONV, 1))
+ return true;
+ *cs= tmp.collation;
+ return false;
  }
 
 public:

sql/item_cmpfunc.cc

@@ -253,15 +253,6 @@ static uint collect_cmp_types(Item **items, uint nitems, bool skip_nulls= FALSE)
  return found_types;
 }
 
-static void my_coll_agg_error(DTCollation &c1, DTCollation &c2,
- const char *fname)
-{
- my_error(ER_CANT_AGGREGATE_2COLLATIONS, MYF(0),
- c1.collation->name,c1.derivation_name(),
- c2.collation->name,c2.derivation_name(),
- fname);
-}
-
 
 /*
  Test functions
@@ -653,39 +644,6 @@ bool get_mysql_time_from_str(THD *thd, String *str, timestamp_type warn_type,
 }
 
 
-/**
- Aggregate comparator argument charsets for comparison.
- One of the arguments ("a" or "b") can be replaced,
- typically by Item_string or Item_func_conv_charset.
-
- @return Aggregation result
- @retval false - if no conversion is needed,
- or if one of the arguments was converted
- @retval true - on error, if arguments are not comparable.
-
- TODO: get rid of this method eventually and refactor the calling code.
- Argument conversion should happen on the Item_func level.
- Arg_comparator should get comparable arguments.
-*/
-bool Arg_comparator::agg_arg_charsets_for_comparison()
-{
- DTCollation tmp;
- if (tmp.set((*a)->collation, (*b)->collation, MY_COLL_CMP_CONV) ||
- tmp.derivation == DERIVATION_NONE)
- {
- my_coll_agg_error((*a)->collation, (*b)->collation, owner->func_name());
- return true;
- }
- if (agg_item_set_converter(tmp, owner->func_name(),
- a, 1, MY_COLL_CMP_CONV, 1) ||
- agg_item_set_converter(tmp, owner->func_name(),
- b, 1, MY_COLL_CMP_CONV, 1))
- return true;
- m_compare_collation= tmp.collation;
- return false;
-}
-
-
 /**
  Prepare the comparator (set the comparison function) for comparing
  items *a1 and *a2 in the context of 'type'.
@@ -717,7 +675,7 @@ int Arg_comparator::set_cmp_func(Item_func_or_sum *owner_arg,
  We must set cmp_collation here as we may be called from for an automatic
  generated item, like in natural join
  */
- if (agg_arg_charsets_for_comparison())
+ if (owner->agg_arg_charsets_for_comparison(&m_compare_collation, a, b))
  return 1;
  }
 

sql/item_cmpfunc.h

@@ -60,7 +60,6 @@ class Arg_comparator: public Sql_alloc
  // when one of arguments is NULL.
  int set_compare_func(Item_func_or_sum *owner, Item_result type);
  int set_cmp_func(Item_func_or_sum *owner_arg, Item **a1, Item **a2);
- bool agg_arg_charsets_for_comparison();
 
  int compare_temporal(enum_field_types type);
  int compare_e_temporal(enum_field_types type);

sql/item_func.h

@@ -187,23 +187,6 @@ class Item_func :public Item_func_or_sum, public Used_tables_and_const_cache
  else
  max_length= (uint32) max_result_length;
  }
- bool agg_arg_charsets(DTCollation &c, Item **items, uint nitems,
- uint flags, int item_sep)
- {
- return agg_item_charsets(c, func_name(), items, nitems, flags, item_sep);
- }
- /*
- Aggregate arguments for comparison, e.g: a=b, a LIKE b, a RLIKE b
- - don't convert to @@character_set_connection if all arguments are numbers
- - don't allow DERIVATION_NONE
- */
- bool agg_arg_charsets_for_comparison(DTCollation &c,
- Item **items, uint nitems,
- int item_sep= 1)
- {
- return agg_item_charsets_for_comparison(c, func_name(),
- items, nitems, item_sep);
- }
  Item *transform(THD *thd, Item_transformer transformer, uchar *arg);
  Item* compile(THD *thd, Item_analyzer analyzer, uchar **arg_p,
  Item_transformer transformer, uchar *arg_t);